This application claims priorities from Japanese Patent Application No. 11-229274 filed Jul. 27, 1999 and from Japanese Patent Application No. 2000-128979 filed Apr. 25, 2000, the entire contents of each of which are incorporated herein by reference for all purposes.
The present invention relates to a structure of an optical switching device having a plurality of light switching sections that are switched in an interlocking manner for facilitating the supervision over the state of connection of transmitting media at the respective light switching sections, and a method therefor. The invention further relates to an optical switching device having a plurality of light switching sections of one-input and two-outputs type in which a loss of light is low.
In connection with an optical switching module of the simultaneous switching type comprising integrated light switching sections for changing the state of connection of a plurality of optical fibers at a time (hereinafter referred to as an optical switching module), an optical switching module of the type described in Japanese patent Laid-Open NO. 133321/1999 is known. A conceivable device to which such an optical switching module is applied is, for example, an optical cross connect apparatus. However, an optical cross connect apparatus having such a structure has never been manufactured practically so far.
Accordingly, the first object of the invention is to facilitate the supervision over the state of connection of each light transmission medium in order to keep reliability of the optical switching device including an optical switching module. The second object of the invention is to facilitate the supervision over the state of connection of each light transmission medium and to increase the reliability of the supervision. The third object of the invention is to provide an optical switching module that is able to supervise the state of connection easily.
In order to achieve the first object, the optical switching device according to the invention comprises an optical switching module including a first light switching section for switching the input of a light or the destination of a received light and a second light switching section to be switched conjointly with the first light switching section, a first light source for emitting a light to be supplied to the first switching section, and a receiver for detecting a light from the first switching section and supplying supervised information based on the detected result.
The switching device may further comprise a supervisory control circuit that receives the incoming supervised information and controls the action of the optical switching module according to the supervised information.
The receiver according to the invention may comprise for example, a photodetector for converting a light received from the first switching section into electric signals and a discrimination decision circuit for comparing the output from the photodetector with a threshold value and supplying the compared result as supervised information.
According to another embodiment of the invention for achieving the first object described above, the optical switching device comprises a first optical switching module including a first light switching section for switching the input of a light and the destination of a received light and a second switching section to be switched conjointly with the first light switching section, a second optical switching module including a third light switching section for switching the input of a light or the destination of a received light and a forth switching section to be switched conjointly with the third switching section, an optical star coupler for dividing a received light into a light to be supplied to the first switching section in the first optical switching module and a light to be supplied into the third switching section in the second optical switching module, a first light source for emitting a light to be supplied to the optical star coupler, a first receiver for detecting a light emitted from the first switching section in the first optical switching module and supplying supervised information according to the detected result, and a second receiver for detecting a light emitted from the third switching section in the second optical switching module and supplying supervised information according to the detected result.
The switching device may further comprise a supervisory control circuit for receiving supervised information and controlling the action of the optical switching modules according to the supervised information.
The first receiver according to the invention may comprise, for example, at least a photodetector for converting a light received from the first switching section in the first optical switching module into electric signals, and a discrimination decision circuit for comparing the output from the photodetector with a threshold value and outputting the compared result as supervised information.
In order to achieve the second object, each of two optical switching devices according to the invention comprises a second light source for emitting a light, and a light switch for selectively leading either one of a light emitted from the first light source or a light emitted from the second light source into the first switching section or into the optical star coupler.
In order to achieve the third object, the invention provides an optical switching module comprising two members moving relative to each other, two light switching sections for switching the input of a light or the destination of a received light conjointly with the relative movement of the two members, and a receiver for detecting a light emitted from one of the two light switching sections and outputting the supervised information according to the detected result.